The influence of age on the prevalence of hepatitis C virus
subtypes 1a and 1b

The distribution of hepatitis C virus (HCV) genotypes was
determined in isolates of 447 chronically HCV-infected German
patients by nucleotide sequencing. Of these, 206 (46.1%) were
infected with the subtype 1a, 215 (48.1%) with subtype 1b, 2 (0.4%)
with subtype 1c, 9 (2.0%) with subtype 3a, and 15 (3.4%) with
subtype 4a. Subtype 1a was predominant in those < 40 years old
(62.6%) and was associated with the risk factor of intravenous drug
addiction and with shorter duration of disease. Conversely, subtype
1b was more frequent in patients > 50 years old (84.7%; P <
.001) and was associated with the risk factor of blood transfusions
and with longer duration of disease. These data suggest that a
shift from subtype 1b to subtype 1a occurred in the population
studied. An increase in HCV infection with subtype 1a and a
diminution of subtype 1b in the future can be expected.